This is a tragedy of our scosiety. He is worried for a message being not kosher, more than pushing away a Jew!
All these breaches of holocho can be fixed now. These are minor issues compared to the fact that the cast majority of Jews in the world are completely separated from Judaism!
And this attitude that protecting yourself is more important than reaching out to a fellow Jew is the cause of it.
This story is very strange and it is extremely unlikely anything like this has ever happened before or cab happen again. It takes insane talent and intellectual to be able to pull of such a scam.
Why from this story you take a Mussar haskell to mistrust everyone. But from the everyday situation on the streets you learn nothing.
Because you are worried about a not kosher mezzanine, not Hashems children who will not even have Jewish offspring, forget hang a mezuza.